imageio: fps no longer supported, use duration instead

[xtfocus]

https://github.com/polakowo/vectorbt/blob/8c040429ac65d43ea431dc2789bf4787dd103533/vectorbt/utils/image_.py#LL74C1-L74C72

Clearly vbt.save_animation is still using fps as argument in imageio.get_writer, which doesn't support fps anymore, One quick fix should be changing this line to

with imageio.get_writer(fname, duration=fps // 5, **writer_kwargs) as writer:

[polakowo]

Thanks. Isn't duration in milliseconds? So it would become duration=1000 / fps.

[polakowo]

Fixed in 0.25.4.